MOSCOW—Ukrainian President
Petro Poroshenko
and his Russian counterpart
Vladimir Putin
said the cease-fire struck between Kiev and pro-Russian separatists on Friday was being observed on the whole, according to similar statements from the Kremlin and Kiev on Saturday.

In a phone call, the two presidents "discussed steps to make the cease-fire permanent in nature," the statement on Ukraine's presidential site said. They also discussed humanitarian-aid deliveries to the regions struck by the conflict, according to both statements.

Messrs. Putin and Poroshenko discussed the monitoring of the cease-fire by the Organization for Security and Cooperation in Europe, the statements said.

The Russian Foreign Ministry said in a statement earlier Saturday that the European Union "is practically sending a signal of direct support to the 'party of war' in Kiev, which is not happy with the results of the Minsk meeting."

"Instead of feverishly searching for ways to hurt the economies of its own countries and Russia, the European Union would do better to work on supporting the economic revival of the Donbas region," the industrialized rebel stronghold in eastern Ukraine, the statement said.

Earlier reports from both sides—Kiev's army and the rebels—said the truce was for the most part holding. Both the Ukrainian army and the rebels, however, came out saying that occasional provocations took place.

"We have recorded a series of provocations by the rebels. They fired on our antiterrorism units on 28 occasions (on Friday), with 10 of those coming after the cease-fire," Ukraine's National Security and Defence Council spokesman Col.
Andriy Lysenko
said Saturday, Interfax reported. These instances, however, didn't necessarily constitute a full-fledged cease-fire breach since it took some time for the written orders of the cease-fire to travel to the rebels.

Ukrainian troops and military didn't leave their posts following the cease-fire. They remained near the Ukrainian port city of Mariupol, which has recently become another center of heavy fighting.

The local administration in Luhansk said on its website Saturday that it would use the cease-fire as an opportunity to begin rebuilding infrastructure in the city and restore the supply of electricity, gas and running water.

An abandoned Ukrainian army tank in the village of Kominternove on Saturday.
Associated Press

A prisoner exchange monitored by the Organization for Security and Cooperation in Europe was also scheduled to begin on Saturday. Col. Lysenko estimated the number of prisoners to be released by the rebels at "more than 200" on Saturday, Interfax reported.

Konstantin Knyrik,
a spokesman for a separatist group called the South East Front, couldn't provide the exact number of prisoners up for exchange. "We will begin exchanging prisoners already today. This isn't an instantaneous process, it will be happening every day," he was quoted by Interfax as saying.

Ukrainian Security and Defense Council official Vasily Vovk told Interfax that the council had given the separatists lists of captured Ukrainian troops. He didn't provide the number of prisoners.

Ukrainian presidential aide
Irina Gerashchenko
said prisoners should be released within the next seven days, Interfax reported. She spoke of hundreds of Ukrainian prisoners eligible for release as a result of the cease-fire, according to the news agency.

The truce leaves the pro-Russian separatists with a large area of territory under their control and represents a major win for Mr. Putin, who had annexed the breakaway Ukrainian region of Crimea in March despite sanctions by the West.

The peace deal—reached in Belarus's capital, Minsk, among representatives of Ukraine and the two separatist republics in Donetsk and Luhansk, as well as Russia's ambassador to Kiev and an official from the Organization for Security and Cooperation in Europe, which will monitor the cease-fire—was described as a series of 12 steps toward ending the five-month conflict that has cost at least 2,000 lives.

The first step, the cease-fire, was to be followed by the prisoner exchange and delivery of humanitarian aid on Saturday. But the rest of the package, including how much autonomy the rebel-held areas will gain, remained murky.

European Union countries agreed Friday to expand their sanctions list on Moscow, with the U.S. expected to follow suit soon. The package included cutting off access to capital markets for more Russian state-owned companies, extending restrictions on sales of dual-use (civilian and military) goods, and targeting another two dozen officials for asset freezes and travel bans, according to several diplomats. It was expected to be adopted Monday and take effect Tuesday.

North Atlantic Treaty Organization leaders wrapped up their summit in Wales agreeing to establish a rapid-reaction force that would be able to move quickly into any trouble spots in Eastern Europe.

The so-called spearhead force is intended primarily to deter Russia from intervening in former Soviet-bloc countries that are now members of the 28-nation alliance—and have been watching events in neighboring Ukraine with increasing alarm.

"Here in Wales, we've left absolutely no doubt—we will defend every ally," said President
Barack Obama
on Friday.